An acoustic wave device is used for a mobile communication filter, or the like. It is known that wirings connected between elements such as acoustic wave elements formed on a substrate or wirings connected between an element and an external terminal formed on the substrate are made to intersect via an air gap (see Japanese Laid-open Patent Publication Nos 7-321425, 2005-109060, 2006-278431, and 2012-9989).
When the wirings are made to intersect via the air gap, a parasitic capacitance between the wirings can be reduced. However, in a process for grinding a rear side of the substrate and a lift-off process of a wiring for example, the wiring may be damaged when a pressure is applied to the wiring.